evidence on which dry land has been inferred to exist
during the formation of the Coal Measures, and comes to the conclusion
that the land was covered by water, confirming Brongniart's opinion that
Sigillaria was an aquatic plant. He believes the Sigillaria "grew in
water, on the deposits where it is now discovered, and that it is the
plant which in a great measure contributed to the formation of our
valuable beds of coal." (Loc. cit., page 193.)) Do you remember how
savage you were long years ago at my broaching such a conjecture?

LETTER 556. TO L. HORNER. Down [1846?].

I am truly pleased at your approval of my book (556/1. "Geological
Observations on South America," London, 1846.): it was very kind of
you taking the trouble to tell me so. I long hesitated whether I
would publish it or not, and now that I have done so at a good cost of
trouble, it is indeed highly satisfactory to think that my labour has
not been quite thrown away.

I entirely acquiesce in your criticism on my calling the Pampean
formation "recent" (556/2. "We must, therefore, conclude that the
Pampean formation belongs, in the ordinary geological sense of the word,
to the Recent Period." ("Geol. Obs." page 101).); Pleistocene would have
been far better. I object, however, altogether on principle (whether I
have always followed my principle is another question) to designate any
epoch after man. It breaks through all principles of classification
to take one mammifer as an epoch. And this is presupposing we know
something of the introduction of man: how few years ago all beds earlier
than the Pleistocene were characterised as being before the monkey
epoch. It appears to me that it may often be convenient to speak of an
Historical or Human deposit in the same way as we speak of an Elephant
bed, but that to apply it to an epoch is unsound.

I have expressed myself very ill, and I am not very sure that my notions
are very clear on this subject, except that I know that I have often
been made wroth (even by Lyell) at the confidence with which people
speak of the introduction of man, as if they had seen him walk on the
stage, and as if, in a geological chronological sense, it was more
important than the entry of any other mammifer.

You ask me to do a most puzzling thing, to point out what is newest in
my volume, and I found myself incapable of doing almost the same for
Lyell. My mind goes from point to point without deciding: what has
interested ones